The 1924 Los Angeles pneumonic plague outbreak began October 30, 1924, and was declared fully contained on November 13, 1924. It represented the first time plague had emerged in Southern California. Previously, plague outbreaks had arisen in San Francisco and nearby Oakland marking the first time plague had emerged in California, the Los Angeles outbreak began on October 30, lasted two weeks, and killed 30 people. Public health officials credited the lessons learned from the San Francisco outbreak coupled with swiftly implemented measures, including hospitalization of the sick and all their contacts, a neighborhood quarantine, and a large-scale rat eradication program, with saving lives.[1][2][3][4]

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Traceback analysis to identify the index-patient revealed that the outbreak actually began sometime in late September or early October, 1924 when a 51-year-old man named Jesús Lujan, living in the Macy Street district near downtown Los Angeles, fell ill with fever and a painful lump in his groin. Prior to symptoms, Lujan had discovered a decaying rat under his house and picked it up and threw it in the trash. Within that same week, Lujan's fifteen-year-old daughter, Francisca (Concha), also fell ill, she complained of fever and respiratory distress. A physician called to the house misdiagnosed the daughter with 'lobar pneumonia' which found out to be secondary plague pneumonia, the physician also misdiagnosed Lujan's bubonic plague as a venereal disease due to his enlarged lymph node. Even the City health officers' confirmation of the disease as pneumonia plague, the disease was referred as "strange malady," "pneumonia," "virulent pneumonia," or "malignant pneumonia" until November 6.[1][5] Investigators believed that Jesús Lujan initially contracted the bubonic form of plague. Left untreated, bubonic plague can move to the lungs and cause a secondary pneumonic infection,[6] as Lujan's end-stage symptoms included bloody sputum, it's believed his had converted to the pneumonic form. And because he fell ill before any of the others, Jesús Lujan was identified as the index-patient.

A week later, Francisca Lujan died. A young pregnant neighbor, Lucena Samarano, who had been caring for Francesca also developed the same respiratory symptoms and died days later. A Catholic priest, Father M. Brualla, who had administered last rites to the victims and said the requiem Mass for Samarano, as well as a dozen or so of the congregants at her funeral, developed the same respiratory symptoms and died days later. Within a week, Lucena Samarano's entire family of eight had died,[1][5] the plague serum was arrived in Los Angeles on November 5, which had been requested by the Los Angeles County General Hospital and the acting health officer of the City Health Department, but it was secured in time to be used and used in only one case.[1]

On October 30, 1924, the Los Angeles County Hospital pathologist, Dr. George Maner, identified plague as the cause of the illness. Dr. Maner identified it from a serum sample from a patient who had died after attending Lucena Samarano's funeral, he notified the City Health Department as well as state officials. City health officials quarantined an eight-block area Clara Street where the funeral had taken place as well as a six-block area in the Belevdere district after Jesǘs Lajun was identified as the index-patient.

Within the quarantined area, the health department set up a temporary laboratory to quickly identify new cases, at the same time, the city began a citywide rat and ground squirrel extermination program. Infected rats were found in downtown, Beverly Hills, and the harbor.

Pneumonic plague is the only form of plague that has person-to-person transmission which occurs during droplet-respiration,[7] and humans can become infected when handling tissue or body fluids of a plague-infected animal. In this case of spread, the pathogen was suspected to transmitted from the decaying rat found under the index patient's house.[1][8]

^Martin Helen Eastman, The History of Los Angeles County Hospital, 1878–1968; and the Los Angeles County University of Southern California Medical Center 1969–1978. (Los Angeles: University of Southern California Press, 1979) 5–7.

1.
San Francisco
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San Francisco, officially the City and County of San Francisco, is the cultural, commercial, and financial center of Northern California. It is the birthplace of the United Nations, the California Gold Rush of 1849 brought rapid growth, making it the largest city on the West Coast at the time. San Francisco became a consolidated city-county in 1856, after three-quarters of the city was destroyed by the 1906 earthquake and fire, San Francisco was quickly rebuilt, hosting the Panama-Pacific International Exposition nine years later. In World War II, San Francisco was a port of embarkation for service members shipping out to the Pacific Theater. Politically, the city votes strongly along liberal Democratic Party lines, San Francisco is also the headquarters of five major banking institutions and various other companies such as Levi Strauss & Co. Dolby, Airbnb, Weebly, Pacific Gas and Electric Company, Yelp, Pinterest, Twitter, Uber, Lyft, Mozilla, Wikimedia Foundation, as of 2016, San Francisco is ranked high on world liveability rankings. The earliest archaeological evidence of habitation of the territory of the city of San Francisco dates to 3000 BC. Upon independence from Spain in 1821, the became part of Mexico. Under Mexican rule, the system gradually ended, and its lands became privatized. In 1835, Englishman William Richardson erected the first independent homestead, together with Alcalde Francisco de Haro, he laid out a street plan for the expanded settlement, and the town, named Yerba Buena, began to attract American settlers. Commodore John D. Sloat claimed California for the United States on July 7,1846, during the Mexican–American War, montgomery arrived to claim Yerba Buena two days later. Yerba Buena was renamed San Francisco on January 30 of the next year, despite its attractive location as a port and naval base, San Francisco was still a small settlement with inhospitable geography. The California Gold Rush brought a flood of treasure seekers, with their sourdough bread in tow, prospectors accumulated in San Francisco over rival Benicia, raising the population from 1,000 in 1848 to 25,000 by December 1849. The promise of fabulous riches was so strong that crews on arriving vessels deserted and rushed off to the gold fields, leaving behind a forest of masts in San Francisco harbor. Some of these approximately 500 abandoned ships were used at times as storeships, saloons and hotels, many were left to rot, by 1851 the harbor was extended out into the bay by wharves while buildings were erected on piles among the ships. By 1870 Yerba Buena Cove had been filled to create new land, buried ships are occasionally exposed when foundations are dug for new buildings. California was quickly granted statehood in 1850 and the U. S. military built Fort Point at the Golden Gate, silver discoveries, including the Comstock Lode in Nevada in 1859, further drove rapid population growth. With hordes of fortune seekers streaming through the city, lawlessness was common, and the Barbary Coast section of town gained notoriety as a haven for criminals, prostitution, entrepreneurs sought to capitalize on the wealth generated by the Gold Rush

2.
Oakland, California
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Oakland /ˈoʊklənd/ is the largest city and the county seat of Alameda County, California, United States. The city was incorporated in 1852, Oaklands territory covers what was once a mosaic of California coastal terrace prairie, oak woodland, and north coastal scrub. Its land served as a resource when its hillside oak and redwood timber were logged to build San Francisco. In the late 1860s, Oakland was selected as the terminal of the Transcontinental Railroad. Following the 1906 San Francisco earthquake, many San Francisco citizens moved to Oakland, enlarging the citys population, increasing its housing stock and it continued to grow in the 20th century with its busy port, shipyards, and a thriving automobile manufacturing industry. Oakland is known for its sustainability practices, including a top-ranking for usage of electricity from renewable resources, in addition, due to a steady influx of immigrants during the 20th century, along with thousands of African-American war-industry workers who relocated from the Deep South during the 1940s. Oakland is the most ethnically diverse city in the country. The earliest known inhabitants were the Huchiun Indians, who lived there for thousands of years, the Huchiun belonged to a linguistic grouping later called the Ohlone. In Oakland, they were concentrated around Lake Merritt and Temescal Creek, in 1772, the area that later became Oakland was claimed, with the rest of California, by Spanish settlers for the King of Spain. In the early 19th century, the Spanish crown granted the East Bay area to Luis María Peralta for his Rancho San Antonio, the grant was confirmed by the successor Mexican republic upon its independence from Spain. Upon his death in 1842, Peralta divided his land among his four sons, Most of Oakland fell within the shares given to Antonio Maria and Vicente. The portion of the parcel that is now Oakland was called encinal—Spanish for oak grove—due to the oak forest that covered the area. In 1851, three men—Horace Carpentier, Edson Adams, and Andrew Moon—began developing what is now downtown Oakland, on May 4,1852, the Town of Oakland incorporated. Two years later, on March 25,1854, Oakland re-incorporated as the City of Oakland, with Horace Carpentier elected the first mayor, the city and its environs quickly grew with the railroads, becoming a major rail terminal in the late 1860s and 1870s. In 1868, the Central Pacific constructed the Oakland Long Wharf at Oakland Point, a number of horsecar and cable car lines were constructed in Oakland during the latter half of the 19th century. The first electric streetcar set out from Oakland to Berkeley in 1891, at the time of incorporation, Oakland consisted of the territory that lay south of todays major intersection of San Pablo Avenue, Broadway, and Fourteenth Street. The city gradually annexed farmlands and settlements to the east and the north, Oaklands rise to industrial prominence, and its subsequent need for a seaport, led to the digging of a shipping and tidal channel in 1902. This resulted in the town of Alameda being made an island

3.
Index case
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An index case will sometimes achieve the status of a classic case in the literature, as did Phineas Gage. The index case may indicate the source of the disease, the spread. The index case is the first patient that indicates the existence of an outbreak, earlier cases may be found and are labeled primary, secondary, tertiary, etc. The term primary case can only apply to infectious diseases spread from human to human. Patient Zero was used to refer to the index case in the spread of HIV in North America. In genetics, the case is the case of the original patient that stimulates investigation of other members of the family to discover a possible genetic factor. In the early years of the AIDS epidemic, a “patient zero” transmission scenario was compiled by Dr. William Darrow, centers for Disease Control and Prevention. This epidemiological study showed how “patient zero” had infected multiple partners with HIV, the CDC identified Gaëtan Dugas as a carrier of the virus from Europe to the United States and spreading it to other men he encountered at gay bathhouses. Journalist Randy Shilts subsequently wrote about Patient Zero, based on Darrows findings, in his 1987 book And the Band Played On, Dugas was a flight attendant who was sexually promiscuous in several North American cities, according to Shilts book. He was vilified for several years as a spreader of HIV. Four years later, Darrow repudiated the studys methodology and how Shilts had represented its conclusions, and more often than not, especially in large disease outbreaks, they’re not. Mary Mallon was a case of a typhoid outbreak in the early 1900s. An apparently healthy carrier, she infected 47 people while working as a cook and she eventually was isolated to prevent her from spreading the disease to others. The first recorded victim of the Ebola virus was a 44-year-old schoolteacher named Mabalo Lokela, 64-year-old Liu Jianlun, a Guangdong doctor, transmitted SARS during a stay in the Hong Kong Metropole Hotel in 2003. A baby in the Lewis House at 40 Broad Street is considered the patient in the 1854 cholera outbreak in the Soho neighborhood of London. Édgar Enrique Hernández may be patient zero of the 2009 swine flu outbreak and he recovered, and a bronze statue has been erected in his honor. Maria Adela Gutierrez, who contracted the virus about the time as Hernández. Two-year-old Emile Ouamouno is believed to be the patient in the 2014 Ebola epidemic in Guinea

4.
Septicemic plague
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Septicemic plague is one of the three main forms of plague. It is caused by Yersinia pestis, a species of bacterium. Septicemic plague is an infection of the blood, most commonly spread by bites from infected fleas. Like some other forms of gram-negative sepsis, septicemic plague can cause disseminated intravascular coagulation, however, it only occurs in a minority of cases of Yersinia infection, so that fewer than 5,000 people a year acquire the disease. It is in fact the rarest of the three varieties, the other forms are bubonic and pneumonic plague. Septicemic plague is a zoonosis, a disease that generally is acquired by humans from animals, such as rodents, goats, sheep and camels also may carry the bacteria. Cats rarely develop clinical signs but can be infected, areas west of the Great Plains of North America are one region where plague-infected animals commonly occur. Animals that commonly carry plague bacteria are largely rodents and Leporidae, Plague has been active in black-tailed prairie dog populations since the 1960s. In the United States outbreaks only occur in the western States and they are devastating, survivors are the ones that happened not to become infected and colonies that recover from a plague outbreak remain at risk. Because black-footed ferrets prey on black-tailed prairie dogs, wild ferret populations also fall victim to sylvatic plague, an outbreak can kill nearly 100% of ferrets in a population, and surviving ferrets commonly face starvation because the prairie dogs are their main prey. Spray-and-vaccinate campaigns have aimed at preventing the spread of the plague among these animals, if the bacteria happen to enter the bloodstream rather than the lymph or lungs, they multiply in the blood, causing bacteremia and severe sepsis. DIC results in depletion of the bodys clotting resources, so that it can no longer control bleeding, consequently, the unclotted blood bleeds into the skin and other organs, leading to red or black patchy rash and to hematemesis or hemoptysis. The rash may cause bumps on the skin that look somewhat like insect bites, usually red, untreated septicemic plague is almost always fatal. Early treatment with antibiotics reduces the mortality rate to between 4 and 15 percent, Death is almost inevitable if treatment is delayed more than about 24 hours, and some people may even die on the same day they present with the disease. Septicemic plague is caused by horizontal and direct transmission, horizontal transmission is the transmitting of a disease from one individual to another regardless of blood relation. Direct transmission occurs from close contact with individuals, through common air usage. The greatest frequency of human infections occur in Africa. The bacteria most commonly appear in areas and wherever there is poor sanitation, overcrowding

5.
Super-spreader
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A super-spreader is a host—an organism infected with a disease—that infects disproportionally more secondary contacts than other hosts also infected with the same disease. A sick human can be a super-spreader, they would be likely to infect others than most people with the disease. Super-spreaders are thus of high concern in epidemiology, the study of the spread of diseases, in epidemics with super-spreading, the majority of individuals infect relatively few secondary contacts. Although loose definitions of super-spreading exist, some effort has made at defining what qualifies as a super-spreading event more explicit. This protocol defines a 99th-percentile SSE as a case which causes more infections than would occur in 99% of infectious histories in a homogeneous population. During the 2003 SARS outbreak in Beijing, China, epidemiologists defined a super-spreader as an individual with transmission of SARS to at least eight contacts, super-spreaders may or may not show any symptoms of the disease. Super-spreaders have been identified who excrete a higher than number of pathogens during the time they are infectious. This causes their contacts to be exposed to higher loads than would be seen in the contacts of non-superspreaders with the same duration of exposure. The basic reproduction number R0 is the number of secondary infections caused by a typical infective person in a totally susceptible population. Some individuals have higher than average individual reproductive numbers and are known as super-spreaders. Through contact tracing, epidemiologists have identified super-spreaders in measles, tuberculosis, rubella, monkeypox, smallpox, Ebola hemorrhagic fever and this shedding rate was calculated in men with similar HIV viral loads. Once treatment for the co-infection had been completed, the HIV shedding rate returned to levels comparable to men without co-infection, herd immunity, or herd effect, refers to the indirect protection that immunized community members provide to non-immunized members in preventing the spread of contagious disease. The greater the number of immunized individuals, the less likely an outbreak can occur because there are fewer susceptible contacts, in epidemiology, herd immunity is known as a dependent happening because it influences transmission over time. As a pathogen that confers immunity to the survivors moves through a susceptible population, even if susceptible individuals remain, their contacts are likely to be immunized, preventing any further spread of the infection. The proportion of individuals in a population above which a disease may no longer persist is the herd immunity threshold. Its value varies with the virulence of the disease, the efficacy of the vaccine, and that is not to say that an outbreak cant occur, but it will be limited. The first cases of SARS occurred in mid-November 2002 in the Guangdong Province of China and this was followed by an outbreak in Hong Kong in February,2003. A Guangdong Province doctor, who had treated SARS cases there, had contracted the virus and was symptomatic, despite his symptoms, he traveled to Hong Kong to attend a family wedding

6.
Black rat
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The black rat, also known as the ship rat, roof rat, house rat, is a common long-tailed rodent of the genus Rattus in the subfamily Murinae. The species originated in tropical Asia and spread through the Near East in Roman times before reaching Europe by the 1st century and they are serious pests to farmers as they eat a wide range of agricultural crops. The black rat was one of the species originally described by Linnaeus in his 18th century work, Systema Naturae. It is the species of the genus Rattus. A typical adult black rat is 12.75 to 18.25 cm long, not including a 15 to 22 cm tail, despite its name, the black rat exhibits several colour forms. It is usually black to brown in colour with a lighter underside. In England during the 1920s, several variations were bred and shown alongside domesticated brown rats and this included an unusual green tinted variety. The black rat also has a coat of black fur. Rattus rattus bone remains that date back to the Norman Period have been discovered in Britain, evidence also suggests that R. rattus existed in prehistoric Europe as well as the Levant during post-glacial periods. The specific origin of the rat is uncertain due to the rats disappearance. Evidence such as DNA and bone fragments suggests that the rats did not originally come from Europe. Rats are resilient vectors for many diseases because of their ability to hold so many infectious bacteria in their blood, Rats played a primary role in spreading bacteria, such as Yersinia pestis, which is responsible for the Justinianic plague and bubonic plague. A recent study indicates that other Asiatic rodents served as reservoirs, from which infections spread as far west as Europe via trade routes. The modern black rat was probably spread across Europe in the wake of the Roman conquest and arose from an ancestor that originated in southeast Asia, the Mediterranean black rats differ genetically from their southeast Asian ancestors by having 38 instead of 42 chromosomes. Therefore, it seems that speciation could have occurred when the rats colonized southwest India, because Rattus rattus is a passive traveler, they could have easily traveled to Europe during the trading between Rome and southwestern Asian countries. Evidence also suggests that, in 321–331 BC, Egyptian birds were preying on Mediterranean rats, Black rats are considered omnivores and eat a wide range of foods, including seeds, fruit, stems, leaves, fungi, and a variety of invertebrates and vertebrates. They are generalists, and thus not very specific in their preferences, which is indicated by their tendency to feed on any meal provided for cows, swine, chickens, cats. They are similar to the squirrel in their preference of fruits and nuts

7.
Microbiology
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Microbiology is the study of microscopic organisms, those being unicellular, multicellular, or acellular. Microbiology encompasses numerous sub-disciplines including virology, mycology, parasitology, microbiologists traditionally relied on culture, staining, and microscopy. However, less than 1% of the present in common environments can be cultured in isolation using current means. Microbiologists often rely on extraction or detection of nucleic acid, either DNA or RNA sequences, viruses have been variably classified as organisms, as they have been considered either as very simple microorganisms or very complex molecules. As an application of microbiology, medical microbiology is often introduced with medical principles of immunology as microbiology and immunology, otherwise, microbiology, virology, and immunology as basic sciences have greatly exceeded the medical variants, applied sciences. The existence of microorganisms was hypothesized for many centuries before their actual discovery, the existence of unseen microbiological life was postulated by Jainism which is based on Mahavira’s teachings as early as 6th century BCE. Paul Dundas notes that Mahavira asserted existence of unseen microbiological creatures living in earth, water, air, in 1546, Girolamo Fracastoro proposed that epidemic diseases were caused by transferable seedlike entities that could transmit infection by direct or indirect contact, or vehicle transmission. However, early claims about the existence of microorganisms were speculative, actual observation and discovery of microbes had to await the invention of the microscope in the 17th century. In 1676, Anton van Leeuwenhoek, who lived most of his life in Delft, Holland, observed bacteria and other microorganisms using a single-lens microscope of his own design. While Van Leeuwenhoek is often cited as the first to observe microbes, Robert Hooke made the first recorded microscopic observation, of the bodies of moulds. It has, however, been suggested that a Jesuit priest called Athanasius Kircher was the first to observe micro-organisms and he was among the first to design magic lanterns for projection purposes, so he must have been well acquainted with the properties of lenses. One of his books contains a chapter in Latin, which reads in translation – Concerning the wonderful structure of things in nature, here, he wrote who would believe that vinegar and milk abound with an innumerable multitude of worms. He also noted that material is full of innumerable creeping animalcule. These observations antedate Robert Hookes Micrographia by nearly 20 years and were published some 29 years before van Leeuwenhoek saw protozoa and 37 years before he described having seen bacteria. Joseph Lister was the first person who said infectious diseases are caused by micro-organism and was first person who used phenol as disinfectant on the wounds of patients. Cohn was also the first to formulate a scheme for the classification of bacteria. Louis Pasteur and Robert Koch were contemporaries of Cohn’s and are considered to be the father of microbiology and medical microbiology. Pasteur is most famous for his series of experiments designed to disprove the widely held theory of spontaneous generation

8.
Virology
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Virology is the study of viruses – submicroscopic, parasitic particles of genetic material contained in a protein coat – and virus-like agents. Virology is considered to be a subfield of microbiology or of medicine, a major branch of virology is virus classification. Viruses can be classified according to the host cell they infect, animal viruses, plant viruses, fungal viruses, another classification uses the geometrical shape of their capsid or the viruss structure. Viruses range in size from about 30 nm to about 450 nm, the shape and structure of viruses has been studied by electron microscopy, NMR spectroscopy, and X-ray crystallography. The latest report by the International Committee on Taxonomy of Viruses lists 5450 viruses, virologists also study subviral particles, infectious entities notably smaller and simpler than viruses, viroids, satellites, and prions. Taxa in virology are not necessarily monophyletic, as the relationships of the various virus groups remain unclear. Viruses arose from mobile genetic elements of cells that became encapsulated in protein capsids, acquired the ability to free from the host cell. Of particular interest here is mimivirus, a giant virus that infects amoebae, is it a simplified version of a parasitic prokaryote, or did it originate as a simpler virus that acquired genes from its host. The evolution of viruses, which occurs in concert with the evolution of their hosts, is studied in the field of viral evolution. While viruses reproduce and evolve, they do not engage in metabolism, do not move, the often-debated question of whether they are alive or not is a matter of definition that does not affect the biological reality of viruses. Herpes simplex causes cold sores and genital herpes and is under investigation as a factor in Alzheimers. Some viruses, known as oncoviruses, contribute to the development of forms of cancer. The best studied example is the association between Human papillomavirus and cervical cancer, almost all cases of cancer are caused by certain strains of this sexually transmitted virus. Another example is the association of infection with hepatitis B and hepatitis C viruses, the study of the manner in which viruses cause disease is viral pathogenesis. The degree to which a virus disease is its virulence. When the immune system of a vertebrate encounters a virus, it may produce specific antibodies which bind to the virus, antibody presence in blood serum is often used to determine whether a person has been exposed to a given virus in the past, with tests such as ELISA. Vaccinations protect against viral diseases, in part, by eliciting the production of antibodies, monoclonal antibodies, specific to the virus, are also used for detection, as in fluorescence microscopy. This mechanism is jump-started by certain vaccinations, RNA interference, an important cellular mechanism found in plants, animals and many other eukaryotes, most likely evolved as a defense against viruses

9.
Pathogenic fungus
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Pathogenic fungi are fungi that cause disease in humans or other organisms. The study of fungi is referred to as medical mycology. Although fungi are eukaryotic organisms, many fungi are also microorganisms. Fungicides, such as ziram are used to protect plants against fungal infections, candida species cause infections in individuals with deficient immune systems. Th1-type cell-mediated immunity is required for clearance of a fungal infection, the most common pathogenic species are Aspergillus fumigatus and Aspergillus flavus. Aspergillus flavus produces aflatoxin which is both a toxin and a carcinogen and which can contaminate foods such as nuts. Aspergillus fumigatus and Aspergillus clavatus can cause allergic disease, some Aspergillus species cause disease on grain crops, especially maize, and synthesize mycotoxins including aflatoxin. Aspergillosis is the group of diseases caused by Aspergillus, the symptoms include fever, cough, chest pain or breathlessness. Usually, only patients with weakened immune systems or with other conditions are susceptible. Cryptococcus neoformans can cause a form of meningitis and meningo-encephalitis in patients with HIV infection. The majority of Cryptococcus species live in the soil and do not cause disease in humans, Cryptococcus neoformans is the major human and animal pathogen. Cryptococcus laurentii and Cryptococcus albidus have been known to occasionally cause moderate-to-severe disease in patients with compromised immunity. Cryptococcus gattii is endemic to parts of the continent of Africa and Australia. Histoplasma capsulatum can cause histoplasmosis in humans, dogs and cats, the fungus is most prevalent in the Americas, India and southeastern Asia. It is endemic in certain areas of the United States, infection is usually due to inhaling contaminated air. Pneumocystis jirovecii can cause a form of pneumonia in people with weakened immune systems, such as premature children, stachybotrys chartarum or black mold can cause respiratory damage and severe headaches. It frequently occurs in houses in regions that are chronically damp, mammalian endothermy and homeothermy are potent nonspecific defenses against most fungi. List of human diseases associated with infectious pathogens Microbiology Mycology Plant pathology Official web site of the European Confederation of Medical Mycology

10.
Parasitology
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Parasitology is the study of parasites, their hosts, and the relationship between them. As a biological discipline, the scope of parasitology is not determined by the organism or environment in question, much research in parasitology falls somewhere between two or more of these definitions. In general, the study of prokaryotes falls under the field of bacteriology rather than parasitology and it is also concerned with the various methods of their diagnosis, treatment and finally their prevention & control. A parasite is an organism that live on or within another organism called the host and these include organisms such as, Plasmodium spp. the protozoan parasite which causes malaria. The four species of malaria parasites infective to humans are Plasmodium falciparum, Plasmodium malariae, leishmania donovani, the unicellular organism which causes leishmaniasis Entamoeba and Giardia, which cause intestinal infections Multicellular organisms and intestinal worms such as Schistosoma spp. Wuchereria bancrofti, Necator americanus and Taenia spp, ectoparasites such as ticks, scabies and lice Medical parasitology can involve drug development, epidemiological studies and study of zoonoses. The study of parasites that cause losses in agriculture or aquaculture operations. Examples of species studied are, Lucilia sericata, a blowfly, the maggots hatch and burrow into the flesh, distressing the animal and causing economic loss to the farmer Otodectes cynotis, the cat ear mite, responsible for Canker. Gyrodactylus salaris, a parasite of salmon, which can wipe out populations which are not resistant. This is the study of structures of proteins from parasites, determination of parasitic protein structures may help to better understand how these proteins function differently from homologous proteins in humans. In addition, protein structures may inform the process of drug discovery, parasites exhibit an aggregated distribution among host individuals, thus the majority of parasites live in the minority of hosts. This feature forces parasitologists to use advanced biostatistical methodologies, parasites can provide information about host population ecology. In fisheries biology, for example, parasite communities can be used to distinguish distinct populations of the fish species co-inhabiting a region. Additionally, parasites possess a variety of specialized traits and life-history strategies that enable them to colonize hosts, understanding these aspects of parasite ecology, of interest in their own right, can illuminate parasite-avoidance strategies employed by hosts. Conservation biology is concerned with the protection and preservation of vulnerable species, the huge diversity between parasitic organisms creates a challenge for biologists who wish to describe and catalogue them. Parasitism Parasitologists Loker, E. & Hofkin, B

11.
Protozoa
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In 21st-century systems of biological classification, the Protozoa are defined as a diverse group of unicellular eukaryotic organisms. Historically, protozoa were defined as single-celled animals or organisms with animal-like behaviors, such as motility, the group was regarded as the zoological counterpart to the protophyta, which were considered to be plant-like, as they are capable of photosynthesis. The terms protozoa and protozoans are now mostly used informally to designate single-celled, non-photosynthetic protists, such as the ciliates, amoebae and flagellates. The term Protozoa was introduced in 1818 for a taxonomic class, in several classification systems proposed by Thomas Cavalier-Smith and his collaborators since 1981, Protozoa is ranked as a kingdom. The seven-kingdom scheme proposed by Ruggiero et al. in 2015, places eight phyla under Protozoa, Euglenozoa, Amoebozoa, Metamonada, Choanozoa, Loukozoa, Percolozoa, Microsporidia and Sulcozoa. This kingdom does not form a clade, but an evolutionary grade or paraphyletic group, from which the fungi, for this reason, the terms protists, Protista or Protoctista are sometimes preferred for the high-level classification of eukaryotic microbes. In 2005, members of the Society of Protozoologists voted to change the name of organization to the International Society of Protistologists. The word protozoa was coined in 1818 by zoologist Georg August Goldfuss, as the Greek equivalent of the German Urthiere, meaning primitive, Goldfuss erected Protozoa as a class containing what he believed to be the simplest animals. Originally, the group included not only microbes, but also some lower animals, such as rotifers, corals, sponges, jellyfish, bryozoa. In 1848, in light of advancements in cell theory pioneered by Theodore Schwann and Matthias Schleiden, von Siebold redefined Protozoa to include only such unicellular forms, to the exclusion of all metazoa. At the same time, he raised the group to the level of a phylum containing two broad classes of microbes, Infusoria, and Rhizopoda. As a phylum under Animalia, the Protozoa were firmly rooted in the old two-kingdom classification of life, criticism of this system began in the latter half of the 19th century, with the realization that many organisms met the criteria for inclusion among both plants and animals. For example, the algae Euglena and Dinobryon have chloroplasts for photosynthesis, as an alternative, he proposed a new kingdom called Primigenum, consisting of both the protozoa and unicellular algae, which he combined together under the name Protoctista. In Hoggss conception, the animal and plant kingdoms were likened to two great pyramids blending at their bases in the Kingdom Primigenum, six years later, Ernst Haeckel also proposed a third kingdom of life, which he named Protista. Despite these proposals, Protozoa emerged as the taxonomic placement for heterotrophic microbes such as amoebae and ciliates. A variety of systems were proposed, and Kingdoms Protista and Protoctista became well established in biology texts. While many taxonomists have abandoned Protozoa as a group, Thomas Cavalier-Smith has retained it as a kingdom in the various classifications he has proposed. As of 2015, Cavalier-Smiths Protozoa excludes several major groups of organisms traditionally placed among the protozoa, including the ciliates, dinoflagellates, Protozoa, as traditionally defined, are mainly microscopic organisms, ranging in size from 10 to 52 micrometers

12.
Helminths
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Helminths, also commonly known as parasitic worms, are large multicellular organisms, which when mature can generally be seen with the naked eye. They are often referred to as intestinal worms even though not all helminths reside in the intestines, for example schistosomes are not intestinal worms, but rather reside in blood vessels. There is no consensus on the taxonomy of helminths, it is more of a commonly used term to describe certain worms with superficial similarities. Many, but not all, of the referred to as helminths belong to the group of intestinal parasites. An infection by a helminth is known as helminthiasis, soil-transmitted helminthiasis, helminths are worm-like organisms living in and feeding on living hosts, receiving nourishment and protection while disrupting their hosts nutrient absorption, causing weakness and disease. Those that live inside the digestive tract are called intestinal parasites and they can live inside humans and other animals. In their adult form, helminths cannot multiply in humans, helminths are able to survive in their mammalian hosts for many years due to their ability to manipulate the immune response by secreting immunomodulatory products. Helminth ova have a shell that protects the eggs against a range of environmental conditions. Helminthology is the study of worms and their effects on their hosts. The word helminth comes from Greek hélmins, a kind of worm, there is no real consensus on the taxonomy of the helminths, particularly with the nematodes. The term helminth contains a number of phyla, many of which are completely unrelated, however, for practical considerations the term is still used nowadays to describe four groups with superficial similarities, the phyla Annelida, Platyhelminths, Nematoda and Acanthocephala. There is in fact no helminth classification, it is an artificial term, the latter are further divided into cestodes and trematodes depending on whether or not they have a segmented body. Ringworm is actually caused by fungi and not by a parasitic worm. Helminths are a group of unrelated organisms which share a similar form. Helminths include members of the taxa, monogeneans, cestodes, nematodes. The number of different helminth species is vast, it is estimated to be one million species. The nematodes are the most diverse of all the helminths with the highest number of species, there may be as many as 300,000 species of parasites affecting vertebrates, and as many as 300 affecting humans alone. Characteristics that are common for all include, Life time

13.
Medical entomology
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The discipline of medical entomology, or public health entomology, and also veterinary entomology is focused upon insects and arthropods that impact human health. Veterinary entomology is included in category, because many animal diseases can jump species and become a human health threat, for example. Thoughtful to have and acquaint with best practice of Med, entomologist to tackle the animal and public health issues together with controlling arthropods born diseases by having Medical Entomologists’ the right hand for bringing the healthy world. Historically, during wars, more people have died due to insect-transmitted diseases, Public health entomology has seen a huge surge in interest since 2005, due to the resurgence of the bed bug, Cimex lectularius. Medical entomologists work in the health arena, dealing with insects that parasitize people, bite, sting. Some personal pests of may vector pathogens, Lice, Fleas, Bedbugs, Ticks, Scabies mites The housefly is a very common, typhoid germs may be deposited on food with the flys faeces. The house fly cause the spread of yaws germs by carrying them from an ulcer to an ordinary sore. Houseflies also transmit poliomyelitis by carrying the virus from infected faeces to food or drink, cholera and hepatitis are sometimes fly-borne. Other diseases carried by houseflies are Salmonella, tuberculosis, anthrax and they carry over 100 pathogens and transmit some parasitic worms. The flies in poorer and lower-hygiene areas usually carry more pathogens, some strains have become immune to most common insecticides. Cockroaches carry disease-causing organisms as they forage, cockroach excrement and cast skins also contain a number of allergens causing responses such as, watery eyes, skin rashes, congestion of nasal passages and asthma. Mosquitoes, Biting Midges, Sandflies, Black flies, Horse Flies, pathogen infection transmitted by insect or other arthropod vectors. Diseases carried by insects and other arthropod vectors affect more than 700 million people every year, dengue fever - Vectors, Aedes aegypti Aedes albopictus threatens -50 million people are infected by dengue annually,25,000 die. Threatens 2.5 billion people in more than 100 countries, malaria - Vectors, Anopheles mosquitoes -500 million become severely ill with malaria every year and more than 1 million die. Leishmaniasis - Vectors, species in the genus Lutzomyia in the New World, bubonic plague - Principal vector, Xenopsylla cheopis At least 100 flea species can transmit plague. Re-emerging major threat several thousand cases per year. High pathogenicity. Sleeping sickness - Vector, Tsetse fly, not all species, sleeping sickness threatens millions of people in 36 countries of sub-Saharan Africa Typhus - Vectors, mites, fleas and body lice 16 million cases a year, resulting in 600,000 deaths annually. Wuchereria bancrofti - most common vectors, the species, Culex, Anopheles, Mansonia

14.
Parasitism
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In biology/ecology, parasitism is a non-mutual relationship between species, where one species, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred primarily to organisms visible to the naked eye, Parasites can be microparasites, which are typically smaller, such as protozoa, viruses, and bacteria. Examples of parasites include the plants mistletoe and cuscuta, and animals such as hookworms, unlike predators, parasites typically do not kill their host, are generally much smaller than their host, and will often live in or on their host for an extended period. Both are special cases of consumer-resource interactions, Parasites show a high degree of specialization, and reproduce at a faster rate than their hosts. Classic examples of parasitism include interactions between vertebrate hosts and tapeworms, flukes, the Plasmodium species, and fleas, parasitism differs from the parasitoid relationship in that parasitoids generally kill their hosts. Parasites reduce host biological fitness by general or specialized pathology, such as parasitic castration and impairment of secondary sex characteristics, Parasites increase their own fitness by exploiting hosts for resources necessary for their survival, e. g. food, water, heat, habitat, and transmission. Although parasitism applies unambiguously to many cases, it is part of a continuum of types of interactions between species, rather than an exclusive category, in many cases, it is difficult to demonstrate harm to the host. In others, there may be no apparent specialization on the part of the parasite, coined in English in 1611, the word parasitism comes from the Greek παρά + σιτισμός feeding, fattening. Parasites are classified based on their interactions with their hosts and on their life cycles, an obligate parasite is totally dependent on the host to complete its life cycle, while a facultative parasite is not. A direct parasite has one host while an indirect parasite has multiple hosts. For indirect parasites, there always be a definitive host. Parasites that live on the outside of the host, either on the skin or the outgrowths of the skin, are called ectoparasites and those that live inside the host are called endoparasites. Endoparasites can exist in one of two forms, intercellular parasites or intracellular parasites, intracellular parasites, such as protozoa, bacteria or viruses, tend to rely on a third organism, which is generally known as the carrier or vector. The vector does the job of transmitting them to the host, an example of this interaction is the transmission of malaria, caused by a protozoan of the genus Plasmodium, to humans by the bite of an anopheline mosquito. Those parasites living in a position, being half-ectoparasites and half-endoparasites, are called mesoparasites. An epiparasite is one that feeds on another parasite and this relationship is also sometimes referred to as hyperparasitism, exemplified by a protozoan living in the digestive tract of a flea living on a dog. Social parasites take advantage of interactions between members of social organisms such as ants, termites, and bumblebees, an extreme example of social parasitism is the ant species of Tetramorium inquilinum of the Alps, which spend their whole lives on the back of Tetramorium host ants. With tiny and deprecated bodies they have evolved for one single task, if they fall off, they most likely would not have the strength to climb back on top of another ant, and eventually they will die

15.
Louse
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Louse is the common name for members of the order Phthiraptera, which contains nearly 5,000 species of wingless insect. Lice are obligate parasites, living externally on warm-blooded hosts which include species of bird and mammal, except for monotremes, pangolins, bats. Lice are vectors of diseases such as typhus, chewing lice live among the hairs or feathers of their host and feed on skin and debris, while sucking lice pierce the hosts skin and feed on blood and other secretions. They usually spend their life on a single host, cementing their eggs. The eggs hatch into nymphs, which three times before becoming fully grown, a process that takes about four weeks. Humans host three species of louse, the louse, the body louse and the pubic louse. The body louse has the smallest genome of any known insect, Lice were ubiquitous in human society until at least the Middle Ages. They appear in folktales, songs such as The Kilkenny Louse House and they commonly feature in the psychiatric disorder delusional parasitosis. A louse was one of the subjects of microscopy, appearing in Robert Hookes 1667 book. Humans host three different kinds of lice, head lice, body lice, and pubic lice, Lice infestations can be controlled with lice combs, and medicated shampoos or washes. Sucking lice are wingless insects ranging from 0.5 to 5 mm in length. They have narrow heads and oval, flattened bodies and they have no ocelli, and their compound eyes are reduced in size or absent. Their antennae are short with three to five segments, and their parts, which are retractable into their head, are adapted for piercing and sucking. There is a pump at the start of the gut. The mouthparts consist of a proboscis which is toothed, and a set of stylets arranged in a cylinder inside the proboscis, contaiing a salivary canal and a food canal. The thoracic segments are fused, the segments are separate. Chewing lice are also flattened and can be larger than sucking lice. They are similar to sucking lice in form but the head is wider than the thorax, there are no ocelli and the mouthparts are adapted for chewing